Notched electrode for electrostimulation lead

ABSTRACT

According to one embodiment, an electrode for use in electrostimulation is provided, where the electrode comprises a notch that operates to substantially eliminate gaseous material from being trapped about the electrode during a molding process of an electrostimulation lead.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application claims priority to co-pending U.S. ProvisionalPatent Application Ser. No. 60/577,311, entitled “NOTCHED ELECTRODE FORELECTROSTIMULATION LEAD,” filed Jun. 5, 2004, the disclosure of which ishereby incorporated herein by reference. This application is related toU.S. patent application Ser. No. 10/872,271, entitled “METHOD OFTREATING DEPRESSION, MOOD DISORDERS AND ANXIETY DISORDERS USINGNEUROMODULATION,” filed Jun. 18, 2004; and U.S. patent application Ser.No. 10/872,277, entitled “METHOD OF TREATING DEPRESSION, MOOD DISORDERSAND ANXIETY DISORDERS USING NEUROMODULATION,” filed Jun. 18, 2004, thedisclosures of which are hereby incorporated herein by reference.

TECHNICAL FIELD

This invention relates generally to the field of electrostimulationtechnology and more specifically to notched electrodes for use in anelectrostimulation lead.

BACKGROUND OF THE INVENTION

Electrostimulation systems are designed to treat neurological disordersand for management of chronic pain. A typical electrostimulation systeminvolves the use of a generator and a stimulation lead having aplurality of electrodes. The generator is coupled to the stimulationlead in order for the electrodes to provide low level electricalimpulses that the stimulation lead applies to the treatment area. Forexample, the stimulation lead may be implanted in the epidural area ofthe body, where the electrical impulses stimulate targeted nerves. Thestimulation may result in the brain replacing the sensation of pain witha more pleasing sensation called paresthesia.

For deep brain stimulation (DBS), the stimulation leads used for spinalcord stimulation (SCS) may not be adequately sized. A smallerstimulation lead, and correspondingly smaller electrodes, may bedesired. However, providing such a smaller stimulation lead has posedsome challenges in that merely resizing lead technology used for SCS hasproven ineffective to provide a smaller stimulation lead, such as oneuseful for DBS, having desirable functional and aesthetic attributes.For example, according to one technique for providing a stimulation leadfor use in SCS, a mold is used to manufacture the stimulation lead wherethe electrodes are placed in the mold, wires are soldered, or otherwiseattached to the electrodes, and a fill material is injected into themold. Injecting the material has posed some challenges because thevolume of the lead is reduced and therefore air, vapor, or other gaseousmaterial may become more easily trapped.

One technique for reducing or eliminating the trapped gaseous materialinvolves injecting the fill material at higher pressure. The highpressure may result in the gas being pushed out of the mold before thefill material cures. This technique, however, may result in theweakening and/or detachment of wire contacts coupled to the electrode.Another technique may involve heating the fill material to decrease itsviscosity in order to more easily fill the areas where gas may betrapped. This technique, however, may result in the discoloration of thematerial due to the increased temperatures, which is aestheticallyunappealing. Additionally, heating the fill material may result in achange of the chemical properties of the resulting lead, which isunacceptable considering the need for bio-compatibility of thestimulation lead and the human body. Consequently, a need exists in theart for other techniques for removing gases.

BRIEF SUMMARY OF THE INVENTION

The present invention is directed to systems and methods which provide anotched electrode for use in electrostimulation. The notched electrode,of embodiments is operable to substantially eliminate gaseous materialfrom being trapped about the electrode during the molding process of anelectrostimulation lead or other stimulation portion body.

According to one embodiment, an electrode is a substantially circularband that is notched at either end, or both ends, of the band. The notchmay have any depth, shape, size, configuration, and placement on theband according to various embodiments of the invention. In one instance,an electrode may have four notches, two at each end of the band. Inanother instance, the electrode may have eight notches, four at each endof the band. However, the notched electrode may include any suitablenumber of notches.

The notch may facilitate the elimination of trapped gas about theelectrode during fabrication of a stimulation lead. The notch may alsobe used for other purposes, such as by providing a view, or “window”, toenable monitoring if the electrode is filled during the injection stepof fabricating a stimulation lead. For example, the notch may be placedon the electrode such that when the fill material occupies the notchedarea, the injection process monitoring the fill level may detect thatthe mold for a stimulation lead is completely filled.

Certain embodiments of the invention may provide one or more technicaladvantages. A technical advantage of one embodiment may be that thenotch allows for trapped gas to escape during the injection process offabricating a stimulation lead or other stimulation portion body suchthat heating the fill material at a high temperature that causesdiscoloration is not necessary. Another technical advantage of oneembodiment may be that the stimulation portion mold may be resized andreshaped without having to redesign it for allowing trapped gas toescape during the injection process. Yet another technical advantage ofone embodiment may be that the notch may be designed having any suitabledimension and shape to produce any aesthetic result desired.Additionally, having a notched electrode at the end of a stimulationportion body may result in the reduction of parts and materials neededto manufacture the stimulation portion body since a window piece may beeliminated.

The foregoing has outlined rather broadly the features and technicaladvantages of the present invention in order that the detaileddescription of the invention that follows may be better understood.Additional features and advantages of the invention will be describedhereinafter which form the subject of the claims of the invention. Itshould be appreciated that the conception and specific embodimentdisclosed may be readily utilized as a basis for modifying or designingother structures for carrying out the same purposes of the presentinvention. It should also be realized that such equivalent constructionsdo not depart from the invention as set forth in the appended claims.The novel features which are believed to be characteristic of theinvention, both as to its design and method of fabrication, togetherwith further objects and advantages will be better understood from thefollowing description when considered in connection with theaccompanying figures. It is to be expressly understood, however, thateach of the figures is provided for the purpose of illustration anddescription only and is not intended as a definition of the limits ofthe present invention.

BRIEF DESCRIPTION OF THE DRAWINGS

For a more complete understanding of the present invention, reference isnow made to the following descriptions taken in conjunction with theaccompanying drawing, in which:

FIG. 1 is a diagram illustrating an example of an electrostimulationsystem using notched electrodes according to an embodiment of thepresent invention.

FIG. 2 is a diagram illustrating a side view of one embodiment of anotched electrode that may be used with a stimulation lead according tothe present invention;

FIG. 3 is a diagram illustrating an end view of the embodiment shown inFIG. 2;

FIG. 4 is a diagram illustrating a side view of another embodiment of anotched electrode that may be used with a stimulation lead according tothe present invention;

FIG. 5 is a diagram illustrating an end view of the embodiment shown inFIG. 4; and

FIG. 6 is a flowchart demonstrating one embodiment of a method formanufacturing a notched electrode for use in electrostimulationaccording to the present invention.

DETAILED DESCRIPTION OF THE INVENTION

Directing attention to FIG. 1, an electrostimulation system 10 usingelectrodes 20 in a stimulation portion, such as lead 12, is shown.Electrostimulation system 10 includes a generator portion, shown asgenerator 30, and stimulation portion, shown as lead 12, that are usedto deliver electrical impulses to nerves in a particular area of thehuman body. Typically, stimulation lead 12 is implanted near thetargeted nerves and is coupled to generator 30. Generator 30 generatesthe electrical impulses, which pass through wires 32 to each electrode20. Stimulation lead 12 includes at least one notched electrode 20located near the end of stimulation lead 12 as shown. Stimulation lead12 may include, however, more notched electrodes 20 without departingfrom the scope of the invention. According to one embodiment, theelectrode 20 that is located at the end closest to generator 30 isreferred to as the terminal end electrode, and the electrode 20 that isclosest to the free end of stimulation lead 12 is referred to as thestimulation end electrode. The terminal end electrode and thestimulation end electrode may include a notch according to the teachingsof the present invention. The terminal end electrode and the stimulationend electrode, however, may have different design and configurationsfrom other electrodes 20, for example, these electrode may not benotched, may be threaded or otherwise adapted to accept a matingcomponent such as a pull relief or tip, etcetera.

According to one embodiment, a mold is used to fabricate stimulationlead 12 having at least one notched electrode 20 that ensures a completeor substantially complete fill of the mold with a resilient materialforming the body of lead 12, enclosing wires 32, and filling the spacesbetween electrodes 20. Accordingly, air, gas, vapor, or any othergaseous material that may become trapped during fabrication issubstantially eliminated through the use of notched electrodes 20.Before injecting the mold with the fill material, electrodes 20 may becoupled to wires 32 in order to receive the electrical impulses fromgenerator 30. The fill material may comprise a resin such aspolyurethane. Any other suitable material may be used as fill material.Specifically, any other suitable bio-compatible material may be used asfill material according to embodiments of the invention. According toone embodiment, electrode 20 is made out of a platinum material. Forexample, electrode 20 may comprise ninety percent platinum and tenpercent iridium. Electrode 20 of various embodiments may comprise anyother suitable compound without departing from the scope of theinvention.

The fill material of embodiments is injected to the mold usingsufficient pressure to prevent the shearing of wires 32 and to allow forthe fill material to press air out of the mold and to occupy the spaceinside and between each electrode 20. Air, or any other gaseousmaterial, may become trapped under electrode 20 during this process. Thenotches are a means to facilitate the substantial elimination of gaseousmaterial. The notch also facilitates filling an inside cavity of eachelectrode 20, which increases the pull strength associated withstimulation lead 12. Additionally, the notch may be used to provide acoupling area for wires 32. In other words, wires 32 may be weldedinside the notch cavity so as to reduce the contact that wires 32 mayhave with the mold during the injection process. By welding wires 32 tothe inside cavity of a notch, the shearing off of wires 32 duringinjection of the mold may be reduced or eliminated. Examples ofembodiments of a notched electrode 20 will be described with referenceto FIGS. 2-5.

Providing at least one notch at each electrode 20 may result in afabrication process of stimulation lead 12 that reduces or substantiallyeliminates vapor lock. Additionally, a lower injection pressure may beused to inject the fill material in the mold used to form stimulationlead 12, thereby ensuring that the wire contact between wires 32 andelectrodes 20 does not weaken or become detached. Other technicaladvantages may become apparent to one of ordinary skill in the art. Forexample, heating the fill material may be unnecessary thereby reducingthe possibility of affecting the chemical properties of the materialscomposing stimulation lead 12. As yet another example, the mold used toform stimulation lead 12 may be resized to achieve the desired width andlength without having to substantially redesign other parameters of themold or pieces for the sole purpose of eliminating trapped gaseousmaterial.

Turning now to FIG. 2, a side view of an embodiment of electrode 20 isshown. According to the illustrated embodiment, electrode 20 comprises abody portion 22 that may be formed in a cylindrical shape. Any othersuitable shape may be used as body portion 22 without departing from thescope of the invention. Body portion 22 has a length 24, which in oneembodiment comprises 0.060±0.001 inches in length. In anotherembodiment, length 24 comprises 0.118″ inches in length. Length 24 maycomprise any other suitable length without departing from the scope ofthe invention.

Notches 40 are located at opposite ends 34 of body portion 22. Notch 40is shown as having a concave shape with a radius that may be selectedusing various criteria. In one embodiment, the sum of the radiuses ofnotches 40 may be selected to not exceed about one third of the overalllength 24. For example, a length 24 comprising 0.60 inches results inthe sum of radiuses of notches 40 to equal about 0.02 inches. Accordingto the illustrated embodiment, each notch 40 comprises a radiusedportion having a radius of 0.008±0.002 inches. Notch 40, however, mayhave any other suitable radius and shape without departing from thescope of the invention. For example, the radius of notch 40 may besmaller or larger depending on the effect desired. To illustrate thepreceding example, notch 40 may be sized with a radius and/or shape thatsubstantially avoids increasing the current density associated with theelectrode and/or avoids points, or sharp edges, that may be associatedwith high current density and high heat concentration.

Although notches 40 are illustrated as being aligned with one another atends 34, each pair of notches 40 may be located independently from thepair of notches 40 of the opposite end 34. The present embodiment showsat each end 34 at least one notch 40, where the center of each notch 40is substantially aligned along central axis 45. However, each pair ofnotches 40 may be located at body portion 22 independently of each otherso that the center of each notch 40 is not substantially aligned alongthe central axis 45. For example, one pair of notches 40 at one end 34may be aligned along a perpendicular axis 48, while another pair ofnotches 40 at the other end 34 may be aligned along central axis 45. Anyother suitable location for each pair of notches 40 may be used withoutdeparting from the scope of the invention.

FIG. 3 is a diagram illustrating an end view of the embodiment shown inFIG. 2. Electrode 20 may include four notches 40 that substantiallyeliminate gaseous material from being trapped about electrode 20 duringa molding process of stimulation lead 12. In the present embodiment,each end 34 comprises two notches 40 and the centers of notches 40 aresubstantially aligned with central axis 45.

Body portion 22 comprises a cylindrical band 42 and a central orifice38. In the present embodiment, cylindrical band 42 comprises an insidediameter 26 of 0.045±0.0005 inches and an outside diameter 28 of0.0600±0.0005 inches. Cylindrical band 42 may comprise any othersuitable dimension. For example, stimulation lead 12 may be resized toaccommodate applications that may need a larger or smaller thicknessresulting in the need for a larger or smaller electrode 20. Althoughcylindrical band 42 is described and illustrated as being substantiallycylindrical, other suitable shapes may be used without departing fromthe scope of the present invention.

According to the illustrated embodiment, central orifice 38 is acylindrical area surrounded by the notched cylindrical band 42. Centralorifice 38 may be used for passing through wires 32. Additionally,central orifice 38 may be filled with fill material during injection ofthe mold associated with stimulation lead 12. It is important to notethat notches 40 may assist the injection process by providing a way toverify that central orifice 38 has been filled with fill material.Although the term “fill” is used, filling central orifice 38 may involveany other suitable process that ensures that a substantial portion ofcentral orifice 38 is occupied by materials other than gaseous material.According to another embodiment (not shown), the inside surface of thecylindrical band 42 may be threaded to facilitate coupling with otherparts of electrostimulation system 10 and to provide additional pullstrength of stimulation lead 12. In the preceding example, the terminalend electrode and the stimulation end electrode may be notched on onlyone end 34 and may be threaded in order to accommodate a stylette guideequipped with a “window” that allows for degassing, as well as providinga visual reference that electrode 20 is completely filled underneath thethreaded contact.

Turning now to FIG. 4, a side view of an embodiment of electrode 20comprising eight notches 40 is shown. Electrode 20 in the presentembodiment may comprise substantially the same dimensions than theelectrode 20 illustrated at FIGS. 2 and 3. According to the presentembodiment, electrode 20 comprises length 24 of 0.060±0.001 inches and aradius of notch 40 of 0.008±0.002 inches. Again, electrode 20 may haveany other suitable dimension, for example, the radius of notch 40 may belarger or smaller, and length 24 may be longer or shorter withoutdeparting from the scope of the invention.

Notches 40 are located at opposite ends 34 of body portion 22. Thepresent embodiment of electrode 20 includes eight notches 40. Fournotches 40 at one side 34 and four notches 40 at the other side 34. Inthe present embodiment, one pair of notches 40 at one end 34 is alignedwith another pair of notches 40 at the other end 34. That is, along theside of body portion 22, the center of a notch 40 at one end 34 and thecenter of another notch 40 at the opposite end 34 are substantiallyaligned along a central axis 45. Although the alignment may be ideal foraesthetic purposes, it is not a critical requirement of the presentinvention. For example, notches 40 at one end 34 of electrode 20 may notbe aligned with notches 40 at the other end 34 of electrode 20.

FIG. 5 is a diagram illustrating an end view of the embodiment shown inFIG. 4. Electrode 20 includes eight notches 40 that substantiallyeliminate gaseous material from being trapped about electrode 20 duringthe molding process of stimulation lead 12. In the present embodiment,each end 34 comprises four notches 40. One pair of notches 40 hascenters substantially aligned with a central axis 45, while another pairof notches 40 has centers substantially aligned with a perpendicularaxis 48. Each pair of notches 40 may be aligned along any other suitableaxis. For example, instead of perpendicular axis 48 an axis being atsixty degrees with reference to central axis 45 may be used to align onepair of notches 40. Any other suitable axis may be used withoutdeparting from the scope of the invention.

As was described with reference to FIG. 3, cylindrical band 42 comprisesan inside diameter 26 of 0.045±0.0005 inches and an outside diameter 28of 0.0600±0.0005 inches. Cylindrical band 42 may, however, comprise anyother suitable dimensions. For example, stimulation lead 12 may beresized to accommodate applications that may need a larger or smallerthickness resulting in the need for a larger or smaller electrode 20.Although cylindrical band 42 is described and illustrated as beingsubstantially cylindrical, other suitable shapes may be used withoutdeparting from the scope of the present invention.

As was described with reference to FIG. 3, central orifice 38 is thecylindrical area surrounded by the notched cylindrical band 42. Centralorifice 38 may be used for passing through wires 32. Additionally,central orifice 38 may be filled with fill material during injection ofthe mold associated with stimulation lead 12. It is important to notethat during notches 40 may assist the injection process by providing away to verify that central orifice 38 has been filled with fillmaterial. Although the term “fill” is used, filling central orifice 38may involve any other suitable process that ensures that a substantialportion of central orifice 38 is occupied by materials other thangaseous material. According to another embodiment (not shown), theinside surface of the cylindrical band 42 may be threaded to facilitatecoupling with other parts of electrostimulation system 10 and to provideadditional pull strength of stimulation lead 12.

FIG. 6 is a flowchart demonstrating one embodiment of a method 100 formanufacturing electrode 20 for use in electrostimulation according tothe present invention. The method begins at step 110 where a wire rod isprovided. The wire rod may be a tube made out of a platinum material.According to one embodiment, the platinum material may comprise ninetypercent platinum and ten percent iridium. The wire rod may comprise anoutside diameter of 0.0600±0.0005 inches and an inside diameter of0.0450±0.0005 inches. Any other suitable dimensions may be used. Forexample, if a smaller electrode 20 is desired, a smaller outsidediameter and inside diameter may be fashioned and the wire rod may bedimensioned accordingly.

At step 120, the wire rod is sliced to produce electrodes. The wire rodmay be sliced at intervals corresponding to length 24. For example, thewire rod may be sliced every 0.060±0.001 inches to produce electrodes20. Any suitable tool may be used to slice the wire rod as long as theprecision of length 24 is preserved.

Notch 40 of electrode 20 is formed at step 130. According to oneembodiment, four notches 40 are formed, two notches 40 at each side 34of electrode 20. According to another embodiment, eight notches 40 areformed, four notches 40 at each side 34. The placement of notches 40 wasdescribed according to the particular descriptions of each embodiment aswas referenced in FIGS. 2 through 5. A wire electrical discharge machinemay be used to form the concave shape of notches 40. Any other suitabletool, however, may be used to form notches 40 without departing from thescope of the invention. Additionally, even though notches 40 aredescribed as having a concave shape with a particular radius, notches 40may comprise any other suitable shape without departing from the scopeof the invention. For example, a notch 40 having a shallow curveresulting in less of a sharp edge between the ridge of the notch 40 andthe surface of end 34 may be used.

At step 140 each electrode 20 may be processed to remove burrs.According to one embodiment, after forming notches 40, each electrode 20is tumbled to remove burrs that may have resulted from slicing and/orforming notches 40. Any suitable process may be used to remove burrswithout departing from the scope of the invention. After removing burrsat step 140 the method terminates.

Method 100 for manufacturing electrodes 20 may modified, such as byomitting or adding steps or performing the steps in any suitable order,without departing from the scope of the invention. For example, slicingthe wire rod to produce electrodes at step 120 may be performed afterforming notches 40 in the electrodes at step 130. Step 130 may in turnbe modified to include boring orifices in the wire rod at intervalswhere the notches are to be located. In this example, an interval may besubstantially the same length as the length of body portion 22.Additionally, the orifice may have a circular shape having a diametersubstantially equal to twice the radius dimension of notch 40.Therefore, in this scenario, the center of each orifice may each bealigned with the slice line in order for each half of the orifice toform at least one notch 40. Any suitable tools may be used to bore theorifices and any other suitable process may be used to locate theorifices and slice notched electrodes 40.

Although the present invention and its advantages have been described indetail, it should be understood that various changes, substitutions andalterations can be made herein without departing from the invention asdefined by the appended claims. Moreover, the scope of the presentapplication is not intended to be limited to the particular embodimentsof the process, machine, manufacture, composition of matter, means,methods and steps described in the specification. As one will readilyappreciate from the disclosure, processes, machines, manufacture,compositions of matter, means, methods, or steps, presently existing orlater to be developed that perform substantially the same function orachieve substantially the same result as the corresponding embodimentsdescribed herein may be utilized. Accordingly, the appended claims areintended to include within their scope such processes, machines,manufacture, compositions of matter, means, methods, or steps.

1. An electrostimulation lead, comprising a plurality of electrodes,wherein at least one electrode comprises a first end surface disposedoutwardly of a body portion, the first end surface comprising at leastone notch.
 2. The electrostimulation lead of claim 1, wherein the atleast one notch is adapted to substantially eliminate gaseous materialfrom being trapped by said at least one electrode during a moldingprocess of the electrostimulation lead.
 3. The electrostimulation leadof claim 1, further comprising four electrodes, each electrodecomprising at least one notch operable to substantially eliminategaseous material from being trapped about each electrode during amolding process of the electrostimulation lead.
 4. Theelectrostimulation lead of claim 1, wherein the at least one electrodecomprises four notches operable to substantially eliminate gaseousmaterial from being trapped about each electrode during a moldingprocess of the electrostimulation lead.
 5. The electrostimulation leadof claim 1, wherein the at least one electrode comprises: at least twonotches disposed outwardly of the first end surface; a second endsurface; and at least two notches disposed outwardly of the second endsurface.
 6. The electrostimulation lead of claim 1, wherein the at leastone electrode comprises eight notches operable to substantiallyeliminate gaseous material from being trapped about each electrodeduring a molding process of the electrostimulation lead.
 7. Anelectrostimulation system, comprising: a generator portion operable togenerate an energy signal; and a stimulation portion coupled to thegenerator portion and comprising a plurality of electrodes operable toreceive the energy signal, at least one electrode of the plurality ofelectrodes comprising a first end surface disposed outwardly of a bodyportion, the first end surface comprising at least one notch.
 8. Theelectrostimulation system of claim 7, wherein the first end surfacecomprises a plurality of notches.
 9. The electrostimulation system ofclaim 7, wherein the at least one electrode comprises a second endsurface disposed outwardly of the body portion, the second end surfacecomprising a plurality of notches.
 10. The electrostimulation system ofclaim 7, wherein the stimulation portion comprises a bio-compatiblematerial.
 11. The electrostimulation system of claim 7, wherein thestimulation portion comprises at least one wire coupled to the generatorportion and at least one electrode of the plurality of electrodes, theat least one wire operable to conduct the electrical signal from thegenerator portion to the at least one electrode, wherein the at leastone wire is coupled to notch.
 12. An electrode for use inelectrostimulation, comprising a notch operable to substantiallyeliminate gaseous material from being trapped about the electrode duringa molding process of stimulation portion body.
 13. The electrode ofclaim 12, further comprising a first end surface disposed outwardly of abody portion, the first end surface comprising at least one of aplurality of notches.
 14. The electrode of claim 13, wherein the firstend surface comprises at least two notches, each notch comprising aconcave portion having a radius in a range between 0.006 inches and0.010 inches.
 15. The electrode of claim 13, wherein the body portioncomprises an outer surface and an internal surface, the outer surfacecomprising an outer diameter in a range between 0.0595 inches and 0.0605inches.
 16. The electrode of claim 15, wherein the internal surfacecomprises an internal diameter in a range between 0.04495 inches and0.0455 inches.
 17. The electrode of claim 13, wherein the body portioncomprises a length in a range between 0.059 inches and 0.061 inches. 18.The electrode of claim 12, wherein the notch comprises a concaveportion.
 19. The electrode of claim 12, further comprising a bodyportion, wherein the body portion comprises an internal surface thatdefines a central orifice operable to pass a wire therethrough.
 20. Theelectrode of claim 12, further comprising a second end surface disposedoutwardly of a body portion, the second end surface comprising one of aplurality of notches.